Breach of promise and Breach of contract

Breach of promise noun - Failure to keep a promise (of marriage).

Breach of contract and breach of promise are semantically related In some cases you can use "Breach of contract" instead a noun phrase "Breach of promise".

Breach of contract noun - A breach of a legal duty; failure to do something that is required in a contract.

Breach of promise and breach of contract are semantically related in unexcused failure to do duty topic. You can use "Breach of promise" instead a noun phrase "Breach of contract".